Picture frame



FIG. 1 is an isometric view of a picture frame;

FIG. 2 is a right side view;

FIG. 3 is a top view;

FIG. 4 is a left side view;

FIG. 5 is a bottom view;

FIG. 6 is a front view; and,

FIG. 7 is a back view.

CLAIM The ornamental design for a picture frame, as shown and described.